There exists a constant search to develop new olefin polymerization catalysts, catalyst activation processes, and methods of making and using catalysts that will provide enhanced catalytic activities and polymeric materials tailored to specific end uses.
One type of catalyst system utilizes metallocene compounds, which have shown promise in tailoring polymer properties. However, there are significant challenges in developing catalysts that can provide custom-made polymers with a specific set of desired properties. It is of interest to develop metallocene-based catalytic systems that can be activated with activating agents that do not require relatively expensive methylaluminoxane, yet still provide relatively high polymerization activities.
Resins produced using metallocene catalysts have captured a significant portion of the linear low density polyethylene (LLDPE) market. Such resins are characterized by a high dart impact. However, some LLDPE films do not exhibit the high clarity and low haze that are required, or at least desired, for many applications. As such, there remains a need for a means to produce LLDPE resins using metallocene catalyst systems that result in films having high clarity and low haze, without sacrificing other properties, such as dart impact strength.